Fuel cells are gaining increasing acceptance and use. One challenge facing designers of fuel cells and fuel cell assemblies is achieving sufficient power plant operating life. There is an ongoing effort to improve the performance of fuel cells including increasing the available power for a given cost and volume of the power plant and increasing the useful life of a power plant.
One advantageous arrangement is shown in U.S. Pat. No. 5,558,955, which includes a non-porous and hydrophobic cathode flow field that provides enhanced acid absorption rate qualities. In one example fuel cell assembly made according to the teachings of that document, the useful operating life of the assembly is approximately five years. It would be advantageous to provide longer-lasting fuel cell assemblies.
Another improvement in fuel cell operation, which tends to extend the useful life of a fuel cell assembly by reducing electrolyte loss is shown in the related U.S. Pat. Nos. 4,345,008 and 4,414,291. A condensation zone is shown in those patents that is useful for condensing an electrolyte from a gas stream before it exits the assembly. Reducing electrolyte loss enhances the ability to sustain a longer-lasting fuel cell operating lifetime.
Another useful feature is shown in U.S. Pat. No. 4,035,551, which provides a hydrophilic electrode substrate that functions as an electrolyte reservoir layer. Such an arrangement enhances electrolyte retaining capabilities.
While there have been individual improvements and advancements in fuel cell operation, no one has provided an integrated approach that maximizes the useful life of a fuel cell assembly while minimizing the size and cost of components such as electrolyte reservoir plates. This invention addresses that need and includes a unique approach to minimizing the rate of performance and acid loss experienced by a fuel cell.